1. Field of the Invention
The present invention relates generally to a safety lock for a window assembly and a method of securing a window assembly using the lock. More particularly, the present invention relates to a novel self-contained, manually operable safety lock for a double-hung window assembly to limit the stroke of a sliding window sash relative to a stationary window sash and a method of securing a double-hung window assembly.
2. Background Art
Double-hung window assemblies commonly are used in modern building construction. A double-hung window assembly typically comprises a window frame and an inner and an outer window sash. The window sashes are contained separately in a pair of tracks located on the window frame to allow vertical or horizontal movement relative to each other.
To provide security, typically, sash locks or fasteners are provided. U.S. Pat. No. 4,923,230 to Simpson discloses a self-contained security lock for a double-hung window comprising (i) a casing, which is adapted to be disposed in a recess of the stile of the outer window sash, having an internal cavity, (ii) a face overlying the cavity, which surrounds the perimeter edges of the recess, (iii) a pivot lug, which is secured to the wall of the casing; (iv) a leaf spring, which is mounted in the casing, and (v) a manually retractable, elongated tumbler, which is pivotally mounted about the lug in the cavity.
The Simpson lock provides security by retarding the displacement of the inner sash relative the outer sash. Indeed, the tumbler is biased by the leaf spring to project through the opening of the casing and face creating a locking position. However, tumblers may over-rotate, which is to say that, in some instances, the inner sash engages the tumbler in such a manner as to cause the tumbler to not engage the back wall of the casing. Consequently, when over-rotated, the lock cannot retard the relative movement of the inner sash with respect to the outer sash.
U.S. Pat. No. 5,536,052 to Maier discloses an improvement to the Simpson sash lock, i.e., a sash lock with an improved tumbler that limits the rotation of the tumbler using an eccentric pivot bore. The Maier sash lock comprises a substantially similar device as Simpson, i.e., a forward-biased tumbler, pivotally mounted about a post in a housing. However, the post of the Maier sash lock extends into a pivot bore in a manner such that the pivot bore, the post, and the biasing spring urge the tumbler to engage the housing continuously. A problem with the Maier sash lock is that biasing springs can malfunction over time.
U.S. Pat. No. 5,542,721 to Allen discloses a sliding window or doorstop comprising a hinged planar tab pivotally mounted in a recess on the interior side of the outer sash or window frame. However, the Allen window stop is prohibitively expensive to install unless the stop is installed as part of the sash manufacturing process. Moreover, the recess must be molded or cut into the outer sash with precision, i.e., within a few thousandths of an inch. Furthermore, a bore to restrain a hinge pin must be drilled or cut on either side of the recess.
Thus, it would be desirable to provide a novel, non-biased sash lock that can be installed economically on double-hung windows that have already been installed and/or on new windows as they are being manufactured.
The present invention provides a method and device for retarding the sliding movement of a first member, e.g., an inner window sash, relative to a second member, e.g., an outer window sash, to provide safety and/or security. The present invention further provides a method and device for retarding the movement of an inner window sash relative to an outer window sash whereby the means for retarding the movement does not entail biasing the device. Finally, the present invention produces a method and device for retarding the movement of an inner window sash relative to an outer window sash that is simple to operate, manufacture, and install.
Accordingly, a security locking device is disclosed. One preferred use of the device is in a double-hung sash window, wherein the stile of the outer sash has a recess in which a sash lock is installed. The device comprises a casing, having an inner and outer perimeter wall and a bottom that define a well with an open end, wherein the casing is disposed in a recess therefor located in the stile of the outer window sash; and a locking tab, having a lifting handle, wherein the locking tab is rotatably mounted in the well of the casing.
Moreover, the present invention includes a system for securing a double-hung window assembly, the system comprising a plurality of recesses, wherein the plurality of recesses is installed in the stile of the outer window sash; and one or more locking devices, wherein the one or more locking devices are installed in an equal number of recesses.
Further, the present invention includes a method of securing a double-hung sash window, the method comprising the steps of: installing one or more recesses in the stile of the outer window sash; installing at least one locking device in one or more of the one or more recesses, wherein the at least one locking device includes a rotatably mounted locking tab that rotates in a direction substantially perpendicular to the direction of movement of the inner window sash; and disposing the locking tab in an open, or locked position, so that the disposed locking tab arrests any further movement of the inner window sash.